"""
simple, elegant templating
(part of web.py)
"""

import re, glob, os, os.path
from types import FunctionType as function
from utils import storage, group, utf8
from net import websafe
from webapi import config

# differences from python:
#  - for: has an optional else: that gets called if the loop never runs
# differences to add:
#  - you can use the expression inside if, while blocks
#  - special for loop attributes, like django?
#  - you can check to see if a variable is defined (perhaps w/ get func?)
# all these are probably good ideas for python...

# todo:
#  inline tuple
#  relax constraints on spacing
#  continue, break, etc.
#  tracebacks

global_globals = {'None':None, 'False':False, 'True': True}
MAX_ITERS = 100000

WHAT = 0
ARGS = 4
KWARGS = 6
NAME = 2
BODY = 4
CLAUSE = 2
ELIF = 6
ELSE = 8
IN = 6
NAME = 2
EXPR = 4
FILTER = 4
THING = 2
ATTR = 4
ITEM = 4
NEGATE = 4
X = 2
OP = 4
Y = 6
LINENO = -1

# http://docs.python.org/ref/identifiers.html
r_var = '[a-zA-Z_][a-zA-Z0-9_]*'

class ParseError(Exception): pass
class Parser:
    def __init__(self, text, name=""):
        self.t = text
        self.p = 0
        self._lock = [False]
        self.name = name
    
    def lock(self):
        self._lock[-1] = True
    
    def curline(self):
        return self.t[:self.p].count('\n')+1
        
    def csome(self):
        return repr(self.t[self.p:self.p+5]+'...')

    def Error(self, x, y=None):
        if y is None: y = self.csome()
        raise ParseError, "%s: expected %s, got %s (line %s)" % (self.name, x, y, self.curline())
    
    def q(self, f):
        def internal(*a, **kw):
            checkp = self.p
            self._lock.append(False)
            try:
                q = f(*a, **kw)
            except ParseError:
                if self._lock[-1]:
                    raise
                self.p = checkp
                self._lock.pop()
                return False
            self._lock.pop()
            return q or True
        return internal
    
    def tokr(self, t): 
        text = self.c(len(t))
        if text != t:
            self.Error(repr(t), repr(text))
        return t
    
    def ltokr(self, *l):
        for x in l:
            o = self.tokq(x)
            if o: return o
        self.Error('one of '+repr(l))
    
    def rer(self, r):
        x = re.match(r, self.t[self.p:]) #@@re_compile
        if not x:
            self.Error('r'+repr(r))
        return self.tokr(x.group())
    
    def endr(self):
        if self.p != len(self.t):
            self.Error('EOF')
        
    def c(self, n=1):
        out = self.t[self.p:self.p+n]
        if out == '' and n != 0:
            self.Error('character', 'EOF')
        self.p += n
        return out

    def lookbehind(self, t):
        return self.t[self.p-len(t):self.p] == t
    
    def __getattr__(self, a):
        if a.endswith('q'):
            return self.q(getattr(self, a[:-1]+'r'))
        raise AttributeError, a

class TemplateParser(Parser):
    def __init__(self, *a, **kw):
        Parser.__init__(self, *a, **kw)
        self.curws = ''
        self.curind = ''
        
    def o(self, *a):
        return a+('lineno', self.curline())
    
    def go(self): 
        # maybe try to do some traceback parsing/hacking
        return self.gor()
    
    def gor(self):
        header = self.defwithq()
        results = self.lines(start=True)
        self.endr()
        return header, results
    
    def ws(self):
        n = 0
        while self.tokq(" "): n += 1
        return " " * n
    
    def defwithr(self):
        self.tokr('$def with ')
        self.lock()
        self.tokr('(')
        args = []
        kw = []
        x = self.req(r_var)
        while x:
            if self.tokq('='):
                v = self.exprr()
                kw.append((x, v))
            else: 
                args.append(x)
            x = self.tokq(', ') and self.req(r_var)
        self.tokr(')\n')
        return self.o('defwith', 'null', None, 'args', args, 'kwargs', kw)
    
    def literalr(self):
        o = (
          self.req('"[^"]*"') or #@@ no support for escapes
          self.req("'[^']*'")
        )
        if o is False:
            o = self.req('\-?[0-9]+(\.[0-9]*)?')
            if o is not False:
                if '.' in o: o = float(o)
                else: o = int(o)

        if o is False: self.Error('literal')
        return self.o('literal', 'thing', o)
    
    def listr(self):
        self.tokr('[')
        self.lock()
        x = []
        if not self.tokq(']'):
            while True:
                t = self.exprr()
                x.append(t)
                if not self.tokq(', '): break
            self.tokr(']')
        return self.o('list', 'thing', x)
    
    def dictr(self):
        self.tokr('{')
        self.lock()
        x = {}
        if not self.tokq('}'):
            while True:
                k = self.exprr()
                self.tokr(': ')
                v = self.exprr()
                x[k] = v
                if not self.tokq(', '): break
            self.tokr('}')
        return self.o('dict', 'thing', x)

    def parenr(self):
        self.tokr('(')
        self.lock()
        o = self.exprr() # todo: allow list
        self.tokr(')')
        return self.o('paren', 'thing', o)
    
    def atomr(self):
        """returns var, literal, paren, dict, or list"""
        o = (
          self.varq() or 
          self.parenq() or
          self.dictq() or
          self.listq() or
          self.literalq()
        )
        if o is False: self.Error('atom')
        return o
        
    def primaryr(self):
        """returns getattr, call, or getitem"""        
        n = self.atomr()
        while 1:
            if self.tokq('.'):
                v = self.req(r_var)
                if not v:
                    self.p -= 1 # get rid of the '.'
                    break
                else:
                    n = self.o('getattr', 'thing', n, 'attr', v)
            elif self.tokq('('):
                args = []
                kw = []
                
                while 1:
                    # need to see if we're doing a keyword argument
                    checkp = self.p
                    k = self.req(r_var)
                    if k and self.tokq('='): # yup
                        v = self.exprr()
                        kw.append((k, v))
                    else:
                        self.p = checkp
                        x = self.exprq()
                        if x: # at least it's something
                            args.append(x)
                        else:
                            break
                            
                    if not self.tokq(', '): break
                self.tokr(')')
                n = self.o('call', 'thing', n, 'args', args, 'kwargs', kw)
            elif self.tokq('['):
                v = self.exprr()
                self.tokr(']')
                n = self.o('getitem', 'thing', n, 'item', v)
            else:
                break
        
        return n
    
    def exprr(self):
        negate = self.tokq('not ')
        x = self.primaryr()
        if self.tokq(' '):
            operator = self.ltokr('not in', 'in', 'is not', 'is', '==', '!=', '>=', '<=', '<', '>', 'and', 'or', '*', '+', '-', '/', '%')
            self.tokr(' ')
            y = self.exprr()
            x = self.o('test', 'x', x, 'op', operator, 'y', y)
        
        return self.o('expr', 'thing', x, 'negate', negate)

    def varr(self):
        return self.o('var', 'name', self.rer(r_var))
    
    def liner(self):
        out = []
        o = self.curws
        while 1:
            c = self.c()
            self.lock()
            if c == '\n':
                self.p -= 1
                break
            if c == '$':
                if self.lookbehind('\\$'):
                    o = o[:-1] + c
                else:
                    filter = not bool(self.tokq(':'))
                    
                    if self.tokq('{'):
                        out.append(o)
                        out.append(self.o('itpl', 'name', self.exprr(), 'filter', filter))
                        self.tokr('}')
                        o = ''
                    else:
                        g = self.primaryq()
                        if g: 
                            out.append(o)
                            out.append(self.o('itpl', 'name', g, 'filter', filter))
                            o = ''
                        else:
                            o += c
            else:
                o += c
        self.tokr('\n')
        if not self.lookbehind('\\\n'):
            o += '\n'
        else:
            o = o[:-1]
        out.append(o)
        return self.o('line', 'thing', out)
    
    def varsetr(self):
        self.tokr('$var ')
        self.lock()
        what = self.rer(r_var)
        self.tokr(':')
        body = self.lines()
        return self.o('varset', 'name', what, 'body', body)

    def ifr(self):
        self.tokr("$if ")
        self.lock()
        expr = self.exprr()
        self.tokr(":")
        ifc = self.lines()
        
        elifs = []
        while self.tokq(self.curws + self.curind + '$elif '):
            v = self.exprr()
            self.tokr(':')
            c = self.lines()
            elifs.append(self.o('elif', 'clause', v, 'body', c))
        
        if self.tokq(self.curws + self.curind + "$else:"):
            elsec = self.lines()
        else:
            elsec = None
        
        return self.o('if', 'clause', expr, 'then', ifc, 'elif', elifs, 'else', elsec)
    
    def forr(self):
        self.tokr("$for ")
        self.lock()
        v = self.setabler()
        self.tokr(" in ")
        g = self.exprr()
        self.tokr(":")
        l = self.lines()

        if self.tokq(self.curws + self.curind + '$else:'):
            elsec = self.lines()
        else:
            elsec = None
        
        return self.o('for', 'name', v, 'body', l, 'in', g, 'else', elsec)
    
    def whiler(self):
        self.tokr('$while ')
        self.lock()
        v = self.exprr()
        self.tokr(":")
        l = self.lines()
        
        if self.tokq(self.curws + self.curind + '$else:'):
            elsec = self.lines()
        else:
            elsec = None
        
        return self.o('while', 'clause', v, 'body', l, 'null', None, 'else', elsec)
    
    def assignr(self):
        self.tokr('$ ')
        assign = self.rer(r_var) # NOTE: setable
        self.tokr(' = ')
        expr = self.exprr()
        self.tokr('\n')
        
        return self.o('assign', 'name', assign, 'expr', expr)
        
    def commentr(self):
        self.tokr('$#')
        self.lock()
        while self.c() != '\n': pass
        return self.o('comment')
        
    def setabler(self):
        out = [self.varr()] #@@ not quite right
        while self.tokq(', '):
             out.append(self.varr())
        return out
    
    def lines(self, start=False):
        """
        This function gets called from two places:
          1. at the start, where it's matching the document itself
          2. after any command, where it matches one line or an indented block
        """
        o = []
        if not start: # try to match just one line
            singleline = self.tokq(' ') and self.lineq()
            if singleline:
                return [singleline]
            else:
                self.rer(' *') #@@slurp space?
                self.tokr('\n')
                oldind = self.curind
                self.curind += '    '
        while 1:
            oldws = self.curws
            t = self.tokq(oldws + self.curind)
            if not t: break
            
            self.curws += self.ws()
            x = t and (
              self.varsetq() or 
              self.ifq() or 
              self.forq() or 
              self.whileq() or 
              self.assignq() or
              self.commentq() or
              self.lineq())
            self.curws = oldws
            if not x:
                break
            elif x[WHAT] == 'comment':
                pass
            else:
                o.append(x)

        if not start: self.curind = oldind
        return o
    
class Stowage(storage):
    def __str__(self): return self.get('_str')
    #@@ edits in place
    def __add__(self, other):
        if isinstance(other, (unicode, str)):
            self._str += other
            return self
        else:
            raise TypeError, 'cannot add'
    def __radd__(self, other):
        if isinstance(other, (unicode, str)):
            self._str = other + self._str
            return self
        else:
            raise TypeError, 'cannot add'
    
class WTF(AssertionError): pass
class SecurityError(Exception):
    """The template seems to be trying to do something naughty."""
    pass




Required = object()
class Template:
    globals = {}
    content_types = {
        '.html' : 'text/html; charset=utf-8',
        '.txt' : 'text/plain',
    }
    
    def __init__(self, text, filter=None, filename=""):
        self.filter = filter
        self.filename = filename
        # universal newlines:
        text = text.replace('\r\n', '\n').replace('\r', '\n').expandtabs()
        if not text.endswith('\n'): text += '\n'
        header, tree = TemplateParser(text, filename).go()
        self.tree = tree
        if header:
            self.h_defwith(header)
        else:
            self.args, self.kwargs = (), {}
    
    def __call__(self, *a, **kw):
        d = self.globals.copy()
        d.update(self._parseargs(a, kw))
        f = Fill(self.tree, d=d)
        if self.filter: f.filter = self.filter

        import webapi as web
        if 'headers' in web.ctx and self.filename:
            content_type = self.find_content_type()
            if content_type:
                web.header('Content-Type', content_type, unique=True)
        
        return f.go()

    def find_content_type(self):
        for ext, content_type in self.content_types.iteritems():
            if self.filename.endswith(ext):
                return content_type
    
    def _parseargs(self, inargs, inkwargs):
        # difference from Python:
        #   no error on setting a keyword arg twice
        d = {}
        for arg in self.args:
            d[arg] = Required
        for kw, val in self.kwargs:
            d[kw] = val

        for n, val in enumerate(inargs):
            if n < len(self.args):
                d[self.args[n]] = val
            elif n < len(self.args)+len(self.kwargs):
                kw = self.kwargs[n - len(self.args)][0]
                d[kw] = val

        for kw, val in inkwargs.iteritems():
            d[kw] = val

        unset = []
        for k, v in d.iteritems():
            if v is Required:
                unset.append(k)
        if unset:
            raise TypeError, 'values for %s are required' % unset 

        return d
    
    def h_defwith(self, header):
        assert header[WHAT] == 'defwith'
        f = Fill(self.tree, d={})

        self.args = header[ARGS]
        self.kwargs = []
        for var, valexpr in header[KWARGS]:
            self.kwargs.append((var, f.h(valexpr)))

    def __repr__(self):
        return "<Template: %s>" % self.filename

class Handle:
    def __init__(self, parsetree, **kw):
        self._funccache = {}
        self.parsetree = parsetree
        for (k, v) in kw.iteritems(): setattr(self, k, v)    
    
    def h(self, item):
        return getattr(self, 'h_' + item[WHAT])(item)
        
class Fill(Handle):
    builtins = global_globals
    def filter(self, text):
        if text is None: return ''
        else: return utf8(text)
        # often replaced with stuff like net.websafe
    
    def h_literal(self, i):
        item = i[THING]
        if isinstance(item, (unicode, str)) and item[0] in ['"', "'"]:
            item = item[1:-1]
        elif isinstance(item, (float, int)):
            pass
        return item
    
    def h_list(self, i):
        x = i[THING]
        out = []
        for item in x:
            out.append(self.h(item))
        return out
    
    def h_dict(self, i):
        x = i[THING]
        out = {}
        for k, v in x.iteritems():
            out[self.h(k)] = self.h(v)
        return out
    
    def h_paren(self, i):
        item = i[THING]
        if isinstance(item, list):
            raise NotImplementedError, 'tuples'
        return self.h(item)
    
    def h_getattr(self, i):
        thing, attr = i[THING], i[ATTR]
        thing = self.h(thing)
        if attr.startswith('_') or attr.startswith('func_') or attr.startswith('im_'):
            raise SecurityError, 'tried to get ' + attr
        try:
            if thing in self.builtins:
                raise SecurityError, 'tried to getattr on ' + repr(thing)
        except TypeError:
            pass # raised when testing an unhashable object
        try:
            return getattr(thing, attr)
        except AttributeError:
            if isinstance(thing, list) and attr == 'join':
                return lambda s: s.join(thing)
            else:
                raise
    
    def h_call(self, i):
        call = self.h(i[THING])
        args = [self.h(x) for x in i[ARGS]]
        kw = dict([(x, self.h(y)) for (x, y) in i[KWARGS]])
        return call(*args, **kw)
    
    def h_getitem(self, i):
        thing, item = i[THING], i[ITEM]
        thing = self.h(thing)
        item = self.h(item)
        return thing[item]
    
    def h_expr(self, i):
        item = self.h(i[THING])
        if i[NEGATE]:
            item = not item
        return item
    
    def h_test(self, item):
        ox, op, oy = item[X], item[OP], item[Y]
        # for short-circuiting to work, we can't eval these here
        e = self.h
        if op == 'is':
            return e(ox) is e(oy)
        elif op == 'is not':
            return e(ox) is not e(oy)
        elif op == 'in':
            return e(ox) in e(oy)
        elif op == 'not in':
            return e(ox) not in e(oy)
        elif op == '==':
            return e(ox) == e(oy)
        elif op == '!=':
            return e(ox) != e(oy)
        elif op == '>':
            return e(ox) > e(oy)
        elif op == '<':
            return e(ox) < e(oy)
        elif op == '<=':
            return e(ox) <= e(oy)
        elif op == '>=':
            return e(ox) >= e(oy)
        elif op == 'and':
            return e(ox) and e(oy)
        elif op == 'or':
            return e(ox) or e(oy)
        elif op == '+':
            return e(ox) + e(oy)
        elif op == '-':
            return e(ox) - e(oy)
        elif op == '*':
            return e(ox) * e(oy)
        elif op == '/':
            return e(ox) / e(oy)
        elif op == '%':
            return e(ox) % e(oy)
        else:
            raise WTF, 'op ' + op
    
    def h_var(self, i):
        v = i[NAME]
        if v in self.d:
            return self.d[v]
        elif v in self.builtins:
            return self.builtins[v]
        elif v == 'self':
            return self.output
        else:
            raise NameError, 'could not find %s (line %s)' % (repr(i[NAME]), i[LINENO])
        
    def h_line(self, i):
        out = []
        for x in i[THING]:
            #@@ what if x is unicode
            if isinstance(x, str):
                out.append(x)
            elif x[WHAT] == 'itpl':
                o = self.h(x[NAME])
                if x[FILTER]:
                    o = self.filter(o)
                else: 
                    o = (o is not None and utf8(o)) or ""
                out.append(o)
            else:
                raise WTF, x
        return ''.join(out)
    
    def h_varset(self, i):
        self.output[i[NAME]] = ''.join(self.h_lines(i[BODY]))
        return ''

    def h_if(self, i):
        expr = self.h(i[CLAUSE])
        if expr:
            do = i[BODY]
        else:
            for e in i[ELIF]:
                expr = self.h(e[CLAUSE])
                if expr:
                    do = e[BODY]
                    break
            else:
                do = i[ELSE]
        return ''.join(self.h_lines(do))
        
    def h_for(self, i):
        out = []
        assert i[IN][WHAT] == 'expr'
        invar = self.h(i[IN])
        forvar = i[NAME]
        if invar:
            for nv in invar:
                if len(forvar) == 1:
                    fv = forvar[0]
                    assert fv[WHAT] == 'var'
                    self.d[fv[NAME]] = nv # same (lack of) scoping as Python
                else:
                    for x, y in zip(forvar, nv):
                        assert x[WHAT] == 'var'
                        self.d[x[NAME]] = y
                
                out.extend(self.h_lines(i[BODY]))
        else:
            if i[ELSE]:
                out.extend(self.h_lines(i[ELSE]))
        return ''.join(out)
    
    def h_while(self, i):
        out = []
        expr = self.h(i[CLAUSE])
        if not expr:
            return ''.join(self.h_lines(i[ELSE]))
        c = 0
        while expr:
            c += 1
            if c >= MAX_ITERS:
                raise RuntimeError, 'too many while-loop iterations (line %s)' % i[LINENO]
            out.extend(self.h_lines(i[BODY]))
            expr = self.h(i[CLAUSE])
        return ''.join(out)

    def h_assign(self, i):
        self.d[i[NAME]] = self.h(i[EXPR])
        return ''

    def h_comment(self, i): pass
    
    def h_lines(self, lines):
        if lines is None: return []
        return map(self.h, lines)
    
    def go(self):
        self.output = Stowage()
        self.output._str = ''.join(map(self.h, self.parsetree))
        if self.output.keys() == ['_str']:
            self.output = self.output['_str']
        return self.output

class render:
    def __init__(self, loc='templates/', cache=None, base=None):
        if cache is None:
            cache = not config.get('debug', False)
        self._loc = loc
        if cache:
            self._cache = {}
        else:
            self._cache = False
        
        self._base = base
    
    def _do(self, name, filter=None):
        if self._cache is False or name not in self._cache:

            tmplpath = os.path.join(self._loc, name) 
            p = [f for f in glob.glob(tmplpath + '.*') if not f.endswith('~')] # skip backup files
            if not p and os.path.isdir(tmplpath):
                return render(tmplpath, cache=self._cache)
            elif not p:
                raise AttributeError, 'no template named ' + name

            p = p[0]
            c = Template(open(p).read(), filename=p)
            if self._cache is not False: self._cache[name] = (p, c)
        
        if self._cache is not False: p, c = self._cache[name]

        if p.endswith('.html') or p.endswith('.xml'):
            if not filter: c.filter = websafe
        return c

    def __getattr__(self, p):
        if self._base:
            return lambda *a, **kw: self._do(self._base)(self._do(p)(*a, **kw))
        else:
            return self._do(p)

def frender(fn, *a, **kw):
    return Template(open(fn).read(), *a, **kw)

def test():
    import sys
    verbose = '-v' in sys.argv
    def assertEqual(a, b):
        if a == b:
            if verbose:
                sys.stderr.write('.')
                sys.stderr.flush()
        else:
            assert a == b, "\nexpected: %s\ngot: %s" % (repr(b), repr(a))
    
    from utils import storage, group

    class t:
        def __init__(self, text):
            self.text = text

        def __call__(self, *a, **kw):
            return TestResult(self.text, Template(self.text)(*a, **kw))

    class TestResult:
        def __init__(self, source, value):
            self.source = source
            self.value = value

        def __eq__(self, other):
            if self.value == other:
                if verbose:
                    sys.stderr.write('.')
            else:
                print >> sys.stderr, 'FAIL:', repr(self.source), 'expected', repr(other), ', got', repr(self.value)
                sys.stderr.flush()
    
    t('1')() == '1\n'
    t('$def with ()\n1')() == '1\n'
    t('$def with (a)\n$a')(1) == '1\n'
    t('$def with (a=0)\n$a')(1) == '1\n'
    t('$def with (a=0)\n$a')(a=1) == '1\n'
    t('$if 1: 1')() == '1\n'
    t('$if 1:\n    1')() == '1\n'
    t('$if 0: 0\n$elif 1: 1')() == '1\n'
    t('$if 0: 0\n$elif None: 0\n$else: 1')() == '1\n'
    t('$if (0 < 1) and (1 < 2): 1')() == '1\n'
    t('$for x in [1, 2, 3]: $x')() == '1\n2\n3\n'
    t('$for x in []: 0\n$else: 1')() == '1\n'
    t('$def with (a)\n$while a and a.pop(): 1')([1, 2, 3]) == '1\n1\n1\n'
    t('$while 0: 0\n$else: 1')() == '1\n'
    t('$ a = 1\n$a')() == '1\n'
    t('$# 0')() == ''
    t('$def with (d)\n$for k, v in d.iteritems(): $k')({1: 1}) == '1\n'
    t('$def with (a)\n$(a)')(1) == '1\n'
    t('$def with (a)\n$a')(1) == '1\n'
    t('$def with (a)\n$a.b')(storage(b=1)) == '1\n'
    t('$def with (a)\n$a[0]')([1]) == '1\n'
    t('${0 or 1}')() == '1\n'
    t('$ a = [1]\n$a[0]')() == '1\n'
    t('$ a = {1: 1}\n$a.keys()[0]')() == '1\n'
    t('$ a = []\n$if not a: 1')() == '1\n'
    t('$ a = {}\n$if not a: 1')() == '1\n'
    t('$ a = -1\n$a')() == '-1\n'
    t('$ a = "1"\n$a')() == '1\n'
    t('$if 1 is 1: 1')() == '1\n'
    t('$if not 0: 1')() == '1\n'
    t('$if 1:\n    $if 1: 1')() == '1\n'
    t('$ a = 1\n$a')() == '1\n'
    t('$ a = 1.\n$a')() == '1.0\n'
    t('$({1: 1}.keys()[0])')() == '1\n'
    t('$for x in [1, 2, 3]:\n\t$x')() == '    1\n    2\n    3\n'
    t('$def with (a)\n$:a')(1) == '1\n'
    t('$def with (a)\n$a')(u'\u203d') == '\xe2\x80\xbd\n'
    t(u'$def with (f)\n$:f("x")')(lambda x: x) == 'x\n'

    j = Template("$var foo: bar")()
    assertEqual(str(j), '')
    assertEqual(j.foo, 'bar\n')
    if verbose: sys.stderr.write('\n')
    

if __name__ == "__main__":
    test()
